Studying the physical­chemical transformations at resource­saving reduction melting of chrome–nickel­containing metallurgical waste

Abstract

We have investigated the physicochemical characteristics of chromium-nickel-containing waste from the production of corrosion-resistant steels and a doped alloy obtained by reduction smelting. This is necessary to determine the parameters that reduce the losses of Ni and Cr during the processing of doped oxide raw materials and using the resulting dopant. It was determined that the alloy with the O/C ratio in the charge in the range of 1.09–1.78 had the γ-Fe and Fe3C phases with alloying elements as substitutional atoms. At O/C=1.78, the phase composition predominantly consisted of γ-Fe with a weak manifestation of Fe3C. A phased O/C change in charge of 1.33 and 1.09 resulted in an increase in the emergence of Fe3C on diffractograms. The microstructure of the chrome-nickel-containing corrosion-resistant steels scale mixture is disordered with the presence of particles of different sizes and shapes. The content of the alloying elements Ni and Cr was 7.65 % wt. and 14.26 % wt., respectively, at the oxygen content at the level of 29.70 % wt. The microstructure of the doped alloy with a different O/C ratio in the charge had a clear manifestation of several phases, characterized by differences in the content of the main alloying elements. The Ni content in the studied areas of different phases varied within 1.41–20.90 % wt., Cr ‒ 1.27–32.90 % wt. According to research, the most acceptable O/C ratio in the charge is 1.78. In this case, reduction was achieved with predominance in the phase composition of γ-Fe with a relatively weak manifestation of residual carbon as the carbide component. In other words, we have determined the indicators for the processing of chromium-nickel-containing industrial wastes and the production of a doped smelting product with a relatively low carbon content. This expands the possibilities of resource saving using the obtained alloy with the replacement of a certain proportion of standard alloying materials in the smelting of carbon-limited steel grades.